Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index 7eebbdf..7284a22 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -22,7 +22,7 @@
* recurse past the end of THREAD_SIZE by default.
*/
#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
-#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
+#define REC_STACK_SIZE (_AC(CONFIG_FRAME_WARN, UL) / 2)
#else
#define REC_STACK_SIZE (THREAD_SIZE / 8)
#endif
@@ -32,12 +32,20 @@
static DEFINE_SPINLOCK(lock_me_up);
-static int recursive_loop(int remaining)
+/*
+ * Make sure compiler does not optimize this function or stack frame away:
+ * - function marked noinline
+ * - stack variables are marked volatile
+ * - stack variables are written (memset()) and read (pr_info())
+ * - function has external effects (pr_info())
+ * */
+static int noinline recursive_loop(int remaining)
{
- char buf[REC_STACK_SIZE];
+ volatile char buf[REC_STACK_SIZE];
- /* Make sure compiler does not optimize this away. */
- memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
+ memset((void *)buf, remaining & 0xFF, sizeof(buf));
+ pr_info("loop %d/%d ...\n", (int)buf[remaining % sizeof(buf)],
+ recur_count);
if (!remaining)
return 0;
else
@@ -67,7 +75,12 @@
void lkdtm_WARNING(void)
{
- WARN(1, "Warning message trigger count: %d\n", warn_counter++);
+ WARN_ON(++warn_counter);
+}
+
+void lkdtm_WARNING_MESSAGE(void)
+{
+ WARN(1, "Warning message trigger count: %d\n", ++warn_counter);
}
void lkdtm_EXCEPTION(void)
@@ -81,9 +94,12 @@
;
}
-void lkdtm_OVERFLOW(void)
+void lkdtm_EXHAUST_STACK(void)
{
- (void) recursive_loop(recur_count);
+ pr_info("Calling function with %lu frame size to depth %d ...\n",
+ REC_STACK_SIZE, recur_count);
+ recursive_loop(recur_count);
+ pr_info("FAIL: survived without exhausting stack?!\n");
}
static noinline void __lkdtm_CORRUPT_STACK(void *stack)
@@ -225,7 +241,7 @@
set_fs(KERNEL_DS);
/* Make sure we do not keep running with a KERNEL_DS! */
- force_sig(SIGKILL, current);
+ force_sig(SIGKILL);
}
/* Test that VMAP_STACK is actually allocating with a leading guard page */
@@ -255,3 +271,69 @@
pr_err("FAIL: accessed page after stack!\n");
}
+
+void lkdtm_UNSET_SMEP(void)
+{
+#ifdef CONFIG_X86_64
+#define MOV_CR4_DEPTH 64
+ void (*direct_write_cr4)(unsigned long val);
+ unsigned char *insn;
+ unsigned long cr4;
+ int i;
+
+ cr4 = native_read_cr4();
+
+ if ((cr4 & X86_CR4_SMEP) != X86_CR4_SMEP) {
+ pr_err("FAIL: SMEP not in use\n");
+ return;
+ }
+ cr4 &= ~(X86_CR4_SMEP);
+
+ pr_info("trying to clear SMEP normally\n");
+ native_write_cr4(cr4);
+ if (cr4 == native_read_cr4()) {
+ pr_err("FAIL: pinning SMEP failed!\n");
+ cr4 |= X86_CR4_SMEP;
+ pr_info("restoring SMEP\n");
+ native_write_cr4(cr4);
+ return;
+ }
+ pr_info("ok: SMEP did not get cleared\n");
+
+ /*
+ * To test the post-write pinning verification we need to call
+ * directly into the middle of native_write_cr4() where the
+ * cr4 write happens, skipping any pinning. This searches for
+ * the cr4 writing instruction.
+ */
+ insn = (unsigned char *)native_write_cr4;
+ for (i = 0; i < MOV_CR4_DEPTH; i++) {
+ /* mov %rdi, %cr4 */
+ if (insn[i] == 0x0f && insn[i+1] == 0x22 && insn[i+2] == 0xe7)
+ break;
+ /* mov %rdi,%rax; mov %rax, %cr4 */
+ if (insn[i] == 0x48 && insn[i+1] == 0x89 &&
+ insn[i+2] == 0xf8 && insn[i+3] == 0x0f &&
+ insn[i+4] == 0x22 && insn[i+5] == 0xe0)
+ break;
+ }
+ if (i >= MOV_CR4_DEPTH) {
+ pr_info("ok: cannot locate cr4 writing call gadget\n");
+ return;
+ }
+ direct_write_cr4 = (void *)(insn + i);
+
+ pr_info("trying to clear SMEP with call gadget\n");
+ direct_write_cr4(cr4);
+ if (native_read_cr4() & X86_CR4_SMEP) {
+ pr_info("ok: SMEP removal was reverted\n");
+ } else {
+ pr_err("FAIL: cleared SMEP not detected!\n");
+ cr4 |= X86_CR4_SMEP;
+ pr_info("restoring SMEP\n");
+ native_write_cr4(cr4);
+ }
+#else
+ pr_err("FAIL: this test is x86_64-only\n");
+#endif
+}